datatyp

2.  Programs transform data from one form to another
◦ Input data  Output data
◦ Stimulus  Response
 Programming languages store and process data in
various ways depending on the type of the data;
consequently, all data read, processed, or written by
a program must have a type
 Two distinguishing characteristics of a programming
language are the data types it supports and the
operations on those data types

3.  A data type is
◦ A set of values AND
◦ A set of operations on those values
 A data type is used to
◦ Identify the type of a variable when the variable is declared
◦ Identify the type of the return value of a function
◦ Identify the type of a parameter expected by a function

4.  When the compiler encounters a declaration for a
variable, it sets up a memory location for it
 An operator used on a variable or variables is legal
only if
◦ The operator is defined in that programming language for a
variable of that type
◦ The variable or variables involved with the operator are of the
same or compatible types

5.  Capital letters A-Z, lowercase letters a-z,
digits 0-9, and the underscore character
 First character must be a letter or underscore
 Usually only the first 32 characters are
significant
 There can be no embedded blanks
 Keywords cannot be used as identifiers
 Identifiers are case sensitive
Identifiers refer to the names of data types, constants,
variables, and functions

6.  Built-in data types
◦ Fundamental data types (int, char, double,
float, void, pointer)
◦ Derived data types (array, string, structure)
 Programmer-defined data types
◦ Structure
◦ Union
◦ Enumeration

7.  void – used to denote the type with no values
 int – used to denote an integer type
 char – used to denote a character type
 float, double – used to denote a floating point
type
 int *, float *, char * – used to denote a
pointer type, which is a memory address type

8. int elevationIndicator;
char inputSymbol;
float totalCost;
int main (void)
{
double grossProduct;
int *temperatureValuePtr;
grossProduct = 4567.89;
inputSymbol = 'a';
return (0);
} // End main

9.  Array – a finite sequence (or table) of
variables of the same data type
 String – an array of character variables
 Structure – a collection of related variables of
the same and/or different data types. The
structure is called a record and the variables in
the record are called members or fields

10. int elevationTable[20];
char inputSymbols[] = "Hello World";
struct operationsStruct
{
double heatReading;
int temperatureValue;
float speedMeter;
char actionCode;
}; // End struct
struct operationsStruct currentOperations;